Strip-like fastener members comprising a great multiplicity of closely-spaced upstanding hook-like projections are used in many different applications for providing both releasable and semi-permanent connection of associated elements. These types of multi-hook fasteners are typically configured for coaction with a multi-loop or likewise "piled" element, with the multiple hooks engaging the closely-spaced multiple loops to provide the desired connecting or gripping action.
Depending upon the configuration of the multi-hook fastener member, many different types of materials and fabrics are adapted for coaction therewith to effect joining of the associated structures. Not only do such fastening devices have many applications for wearing apparel, recreational equipment, covers for cars and boats, and the like, such devices are further being advantageously employed in applications wherein the highly convenient connecting action promotes joining of associated structures in an essentially permanent manner. For example, such fastening devices are finding ever-increasing use in the automotive industry for efficient fabrication and assembly of components such as seats, interior trim, and the like.
Because the multi-hook fastener element of such fastening devices is often most advantageously and efficiently handled and used in an elongated, continuous strip form, various techniques have been developed for manufacture of such multi-hook fasteners in continuous strips. However, the difficulties associated with forming the large number of relatively small hook-like projections required for the desired fastening action has heretofore led those skilled in the art to resort to relatively complex forming devices and/or processes.
By way of example, U.S. Pat. No. 3,147,528, to Erb, discloses an openable injection mold having a large number of projection-forming cavities which open upwardly to a generally flat surface at the top of the mold. The cavities are defined by a series of separable mold plates. In use, a piece of fabric is positioned atop the mold plates, and moldable material is forced through the fabric so that it enters the cavities of the mold, thus forming a multi-hook fastener member. Since the mold itself is of a discrete length, formation of a continuous strip-like fastener member calls for relatively inefficient sequential or stepwise formation of individual segments of the member in end-to-end relation.
U.S. Pat. No. 3,758,657, to Menzin et al, discloses an apparatus for producing a continuous multi-hook fastener member. The apparatus includes a drum-like apparatus which includes a relatively complex arrangement of shiftable plates at its periphery which define cavities for forming hook-like projections. A plastic extruder is provided in close association with the drum so that as the drum rotates, plastic is injected into the hook-shaped cavities and is joined to a backing strip. Removal of the fastener member thus formed is accomplished by inwardly shifting alternate ones of the cavity-defining plates so that the cavities are opened to permit removal of the hook-like projections.
As will be appreciated, the above forming techniques require relatively complex equipment, and overall efficiency suffers due to the required opening of the hook-forming cavities to permit removal of the hook projections therefrom without damage or unacceptable deformation. The present method of forming a multi-hook fastener member affords a substantial improvement in the efficiency with which such members can be formed by permitting continuous formation of such a strip-like fastener member without unduly complex forming machinery.
Referring once again to the configuration of the multi-hook fastener member and its engagement with a multi-loop fastener member, numerous hook-type engaging elements have been known and utilized in the past. For example, the basic type of hook-type engaging element is constructed from a monofilament loop, generally nylon, one leg of which is either cut or removed to transform the loop into a hook. This configuration represents the original concept for such fasteners. As the fasteners developed and their use became more widespread, the fastener member containing the hook-type engaging elements was sometimes replaced with a fastener member having a plurality of mushroom-shaped engaging elements which function in many ways like hooks, but they had different characteristics in certain other ways. For example, with a standard hook surface, the forces required to peel the standard hook/loop separable members were lower than the forces required to peel the mushroom/loop separable members. Also, the shear forces required to separate the members along the interfacial plane of engagement were much greater with mushroom fasteners than with hook fasteners as demonstrated by comparison tests for comparable sized hooks and mushrooms. Still further, it was found that greater peel forces for the mushroom/loop fastener resulted in a much earlier demise of the loop member, thus causing the cycle life for mushroom/loop fasteners to be much lower than hook/loop fasteners.
When the molded hook fasteners manufactured according to the Menzin et al. inventions as described above were developed, it was found that all other factors being equal, the peeling forces required to separate the molded fastener member from a loop member are somewhat higher than those of standard hook/loop fasteners while the shearing forces required to separate the molded hook from a loop member are also greater than standard hook/loop fasteners. The cycle life for both mushroom/loop and molded hook/loop fasteners are comparable. Thus, it is evident that in environments where high shear capability is required, the presently known molded hook fastener members are unable to compensate for many of the deficiencies of the standard hook/loop fastener and that where high shear strength is required, it has been necessary up to now to resort to mushroom/loop fasteners. In such cases, it has also been necessary to accept the inherent loop destructibility of those fasteners in the peel mode.
For example, fastener applications which require substantial strength in shear are legion. One excellent example is in an article of footwear such as shoes, jogging shoes, sneakers or the like. In such cases where standard hook/loop fasteners did not provide the necessary shear force resistance required for the environment, it has been necessary to either accept the lower shear capability of the hook/loop fastener or to utilize the mushroom/loop fastener and to accept its low loop cycle life. In footwear applications, for example, it was sometimes necessary to resort to newly structured straps, pull-ring combinations, etc. to obtain better shear forces and capability. Other applications which often require substantial shear capability include articles of clothing, industrial applications in light duty machinery, hook and loop fastener kits for hanging articles up on a wall, medical applications, etc. The list can readily be expanded by persons skilled in the art. In such cases with prior art separable fasteners, particularly of the woven or knitted type, it was not possible to increase the strength in shear without affecting the strength in peel. For example, a woven monofilament hook was of one cross-sectional dimension throughout and could not be varied at any cross-section to provide a predetermined fastener characteristic as may be required in a particular application.
My invention relates not only to a unique apparatus and method for conveniently and inexpensively producing molded hook-type fastener member as described, but it also relates to a uniquely configured molded hook-type fastener member which may be predesigned above and beyond the basic inventive hook/loop concept to provide all of the peel benefits of standard hook/loop fastener members while simultaneously providing shear resistance comparable to the mushroom/loop fastener member, or lesser or greater, depending upon need, without the loop destruction encountered with such mushroom fastener members.